Implantable access devices

ABSTRACT

An implantable access device which permits the introduction of an external filament such as a catheter, guide wire or optical fiber into a patient for communication with an internal catheter located within the body of the patient. The device includes a housing having inlet and outlet openings and a passageway communicating between the openings. The first sealing mechanism provides resistance to fluid flow through the passageway when the external filament is not present within the device. This first sealing mechanism allows the transfer of fluids through the passageway when the filament is present within the passageway. A second sealing mechanism engages and seals about the exterior perimeter of the external filament when the filament is located within the device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.08/442,722, filed May 15, 1995, Attorney Docket No. 7882-00001/CPN nowU.S. Pat. No. 5,554,117, which is a continuation-in-part of U.S.application Ser. No. 259,053, filed Jun. 13, 1994, now U.S. Pat. No.5,417,656, which is a continuation of U.S. application Ser. No. 148,394,filed Nov. 8, 1993 (now U.S. Pat. No. 5,350,360), which is a divisionalof U.S. application Ser. No. 940,619, filed Sep. 4, 1992 (now U.S. Pat.No. 5,281,199), which is a continuation-in-part of U.S. application Ser.No. 818,626 filed Jan. 10, 1992 (now U.S. Pat. No. 5,226,879), which isa continuation-in-part of U.S. application Ser. No. 654,661 filed Feb.15, 1991 (now U.S. Pat. No. 5,180,365), which is a continuation-in-partof U.S. application Ser. No 539,793 filed Jun. 18, 1990 (now U.S. Pat.No. 5,053,013), which is a continuation-in-part of U.S. application Ser.No. 487,541 filed Mar. 1, 1990 (now U.S. Pat. No. 5,057,084); thedisclosures of which are hereby incorporated by reference and arecollectively referred to as "related applications" herein.

FIELD OF THE INVENTION

This invention relates to devices permitting the introduction of anexternal filament, such as a catheter, into a patient for infusing atherapeutic or diagnostic agent to a desired site or withdrawing fluidfrom the patient or for permitting access by other filaments such as aguide wire, fiber optic sensor etc. to a desired site within the body ofa patient. The device thus enables the filament to communicate eitherdirectly or indirectly, with or without physical contact, with a desiredsite within the body of the patient. More particularly, the inventionrelates to devices which are completely implanted within the body of thepatient. While completely implanted, the present invention is designedso as to facilitate repeated access by the percutaneous route.

BACKGROUND AND SUMMARY OF THE INVENTION

In current human and animal medical practice, there are numerousinstances where therapeutic or diagnostic agents must be delivered to aspecific organ or tissue within the body. One example is the lengthytreatment period where chemotherapy is infused into a central vein on arecurring basis in an attempt to treat widespread sites of malignanttumors. Without a device for intravenous drug infusion, multiple veinpunctures over a lengthy period of time would result in progressivethrombosis, venous sclerosis, and destruction of small diameterperipheral vessels. In other situations, it may be desirable to infusechemotherapy to a localized malignant tumor site. Delivering an agentspecifically to such a site on a regular repetitive basis withoutsurgically implanting an infusion system would prove difficult if notimpossible. Similarly, repeated arterial access is occasionally neededto inject an X-ray dye or contrast agent into an artery for diagnosticpurposes. In still other situations, there is a need to repetitivelyremove a body fluid from a remote body site for analysis. Finally,sensing and physiological measuring devices incorporated into smalldiameter catheters and optical fibers are increasingly being utilizedfor monitoring body processes and could be more easily implementedthrough a properly designed access device with an adequate internaldiameter.

In prior medical practice, percutaneous catheters have been used toprovide vascular or organ access for drug therapy or the withdrawal ofbody fluids. Although such systems generally performed in a satisfactorymanner, numerous problems were presented by such therapy approaches.These problems included, without limitation the substantial carerequirements of the patients, e.g. dressing changes with steriletechniques, a significant rate of infection of the catheter because ofits transcutaneous position, and a high rate of venous thrombosis,particularly if the catheter was located within an extremity vein.

Implantable infusion devices or "ports" have recently become availableand represent a significant advance over transcutaneous catheters.Presently available infusion ports have a number of common fundamentaldesign features. The ports themselves comprise a housing which forms areservoir that can be constructed from a variety of plastic or metalmaterials. A surface of the reservoir is enclosed by a high-density,self-sealing septum, typically made of silicone rubber. Connected to theport housing is an implanted catheter which communicates with a vein orother site within the patient where the infusion of therapeutic agentsis desired. Implantation of such devices generally proceeds by making asmall subcutaneous pocket in an appropriate area of the patient underlocal anesthesia. The implanted catheter is tunnelled to the desiredinfusion site. When the physician desires to infuse or remove materialsthrough the port, a hypodermic needle, which pierces the skin over theinfusion port, is used and placed into the port.

Although the presently available implantable infusion ports generallyoperate in a satisfactory manner, they have a number of shortcomings.Since these devices rely on a compressed rubber septum for sealing andsince large diameter needles can seriously damage the septum, there arelimitations in the diameter of needles which can be used to penetratethe septum. These diameter limitations severely restrict theopportunities provided by the port. In cases where it is desirable toinfuse drugs using a flexible external catheter, the catheter must befed through the needle that penetrates the septum. Such catheters havean extremely small inside diameter and, therefore, impose severelimitations on both the fluid flow rate and limit the types of fiberswhich can be introduced.

During prolonged infusions using a conventional port, the infusionneedle is taped to the patient's skin to hold it in position.Conventional ports do not allow the needle to penetrate deeply into theport. Because of this, a small displacement of the needle can cause theneedle to be pulled from the port. In cases where locally toxicmaterials are being infused, extravasation of such materials can causelocal tissue damage which itself may require corrective surgery such asskin grafting or removal of the damaged tissue.

Presently available implantable drug infusion devices also require asignificant size in order to provide an acceptable target surface areafor the physician who must locate the port and penetrate the septum witha needle. Since structure is required to maintain the septum incompression and provide for self-sealing after the needle is removed,the port housing becomes bulky as the septum size increases. Moreover,presently available infusion ports are difficult to clear if thrombosisoccurs within the port or within the implanted catheter. This isdifficult, if not impossible, because of the relative sizes of acleaning wire which would have to be fed through the penetratinghypodermic needle in order to clear the infusion device and the internalcatheter.

Present infusion ports also have a retained volume beneath theself-sealing septum. The retained volume increases the volume of drugwhich must be administered to enable a desired quantity to reach theinfusion site. This retained volume also poses problems when a physiciandesires to successively deliver multiple drugs to the same infusionsite, particularly when the drugs are incompatible when mixed.Additionally, when it is desired to withdraw blood through the port, theretained volume of the prior art infusion ports comprises an area whereblood clotting can occur. This in turn can interfere with future accessto the site. And finally, in present infusion ports, there is a riskthat the physician attempting to pierce the port septum will notproperly enter it, leading to the possibility of extravasation, whichcan cause significant undesirable consequences as mentioned above, orpiercing of the implanted catheter itself.

The present invention relates to a family of implantable access portswhich provide numerous enhancements over prior art devices. Inaccordance with this invention, an access port is provided whichincorporates the funnel-shaped entrance orifice which narrows down to areduced diameter guide passageway. The guide passageway terminates at aninternal cavity which retains a catheter valve which may be anarticulating type, such as a multi-element leaflet valve assembly. Theport also has an exit passageway which is connected to an implantedcatheter. This specification describes numerous embodiments ofalternative designs of patient access ports of the type described in therelated applications.

In prior embodiments of the present invention, various valving systemswere described and claimed, including leaflet valves, ball valves,"flapper" type valves, etc. Each of these valve configurations isbroadly encompassed by the description "articulating catheter valve" or"articulating valve"; meaning that one or more valve elements aredisplaced in some predictable manner to provide access and seal aroundthe inserted filament and to return to an original position to provide afluid seal against backflow through the valve assembly.

In order to operate successfully, the valve mechanism of the access portmust perform two distinct functions. When the valve is not being usedfor access, the flow of fluids in either direction through the accessport is to be avoided (i.e. "normal condition sealing"). When anexternal catheter is placed into the port, there is a need to sealaround the outer diameter of the catheter to prevent fluid from flowingout of the entrance of the access port instead of through the port exitand into the implanted catheter (i.e. "use condition sealing"). In therelated applications, these two distinct sealing functions weresatisfied by a single valve assembly, which as mentioned before, couldbe a multiple element leaflet valve assembly.

In the present invention, valve configurations are described in whichfeatures providing normal condition sealing of the access port areseparated from the features which provide use condition sealing. Thisalternative configuration is provided in several different specificembodiments. One such embodiment utilizes a check valve in the form ofan elongated tube connected to the port and having an internalpassageway that is normally maintained in a flattened, occludedcondition when the fluid pressure within the passageway is the same asor less than the pressure acting upon the exterior of the valve. Thisvalve provides normal or non-use condition sealing of the passageway. Animplanted internal catheter is attached to this valve and an O-ring maybe located within the access device to provide an additional seal aroundthe perimeter of an inserted filament during actual use of the device.When the external catheter has been inserted into the access device, anda fluid is being infused, the pressure within the occluded conduit isincreased to the point where the passageway inflates and the fluid isdelivered to the desired tissue site through the internal catheter.Other types of fluid pressure actuated valves, as further discussedbelow, could alternatively be used.

In another embodiment, the O-ring or perimeter sealing member may beprovided downstream (or upstream) of the valve which prevents backflowthrough the access port in the normal condition. As used herein, theterms upstream and downstream shall be determined relative to the sourcefor the accessing catheter.

Upon insertion of a filament through the port, the valve is opened andthe filament is inserted until circumferentially engaged by the O-ring.Once such embodiment could include insertion of the accessing catheterthrough the collapsed tube-type of valve described above.

In yet another embodiment similar to the first described above, aball-type check valve is utilized which provides normal conditionsealing.

In another aspect of the present invention, a novel mechanism isprovided to limit the extent to which a flexible filament above apredetermined diameter, such as a twenty (20) gage ANGIOCATH™, can beinserted through the access port. In prior embodiments of thisinvention, as described in the related applications, mechanisms wereprovided where the insertion distance of a rigid filament, such as ahypodermic needle, is limited by features designed for that purpose. Oneneedle stop approach is to provide a bend or redirection in a passagewayeither before of beyond the valve assembly. The bend is such that theinserted needle would be unable to engage the valve assembly due to itsrigidity. A flexible filament, however, is capable of maneuvering a bendin the passageway and as such can be inserted completely through theaccess port and into the implanted catheter which communicates with thedesired site in the patient. There may be instances where it isdesirable to provide a means of limiting the depth of insertion of aflexible filament. In some applications, engagement of the flexiblefilament with the internal catheter can potentially lead to dislodgingof the internal catheter from the discharge fitting of the access portor repositioning it. Moreover, some implanted catheters may not have aninternal diameter sufficient to accommodate the external filament.

According to the present invention, a positive stop feature is providedwhereby an internal flexible filament above a predetermined size isprevented from completely passing through the access port or implantedcatheter. Accordingly, the catheter stop can be utilized to form the usecondition seal of the access device. Slightly, smaller diameterfilaments form a seal with the internal diameter of the passageway whilestill being movable through the entire access port and implantedcatheter. In one embodiment, the internal diameter of the passagewaythrough the discharge fitting of the access port is convergently taperedto a diameter which is less than the external diameter of the insertedfilament. During insertion, the person inserting the flexible filamentwill be able to feel positive engagement of the filament with the stopas further insertion is prevented. This positive stop could also beachieved by progressively decreasing the diameter of the passagewaythrough the discharge fitting in a series of stepped reduced diameterportions. Such a progressively stepped passageway could in turn be usedas a stop for certain diameter catheters. Since engagement with thepositive stop feature creates a seal around the outside of the externalcatheter, these features can be implemented to provide use conditionsealing for multiple sizes of accessing catheter, either by themselvesor in conjunction with "O-rings" provided elsewhere in the port.

In accordance with another aspect of the present invention, an accessport is disclosed where the implanted catheter is shielded from beinginadvertently engaged by a sharp instrument such as a needle or trocarbeing used to access the port. Such engagement might result where theperson inserting the needle or trocar completely misses the entranceorifice defined in the port. In the present invention, such a rigidaccessing instrument is laterally deflected away from the implantedcatheter by the exterior surface contours of the device. For example, apair of curved surfaces can be provided on the exterior of the accessport which laterally diverge from a leading edge at the devicecenterline. As a result, any inserted instrument inadvertently missingthe entrance orifice of the port in traveling along the exterior surfaceof the port will engage one of the two curved surfaces and be deflectedlaterally away from the implanted catheter.

Various accessing approaches are possible using the access ports inaccordance with the present invention including conventional needles,sharp trocars, blunt instruments, and catheter-over-needle combinationssuch as the ANGIOCATH™. Yet another access instrument combines the skinpenetration capabilities of a sharpened metal instrument with theflexibility of an external filament. These devices, also referred to as"self-introducing catheters". While all of the above filaments could beutilized with the present invention, it is believed that its greatestutility will be with a self-introducing catheter or catheter-over-needlevariety.

Additional benefits and advantages of the present invention will becomeapparent to those skilled in the art to which this invention relatesfrom the subsequent description of the preferred embodiments and theappended claims, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an access port assembly in accordancewith this invention incorporating novel internal features and providinga shielding feature for an internal catheter is provided on the exteriorof the access port;

FIG. 2 is a top plan view of a portion of the access port seen in FIG.1;

FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 1;

FIG. 3a is an enlarged view taken along line 3a in FIG. 3;

FIG. 3b is a cross-sectional view similar to that of FIG. 3 showinganother embodiment of the present invention;

FIG. 4 is an exploded view of an articulating valve assembly as used inat least one embodiment of the present invention;

FIG. 5 is a cross sectional view similar to that of FIG. 3 illustratinga second embodiment of a catheter stop according to the principles ofthe present invention;

FIG. 5a is an enlarged sectional view of a portion of a catheter stopseen in FIG. 5 and generally encircled by line 5a;

FIG. 6 is a cross sectional view similar to that seen in FIG. 3illustrating an embodiment of this invention in which normal conditionsealing is provided by an elongated self-flattening or self-occludingtube section which is not penetrated by an inserted catheter or filamentand implementing an O-ring to provide use condition sealing;

FIG. 7 is a cross sectional view similar to that seen in FIG. 6illustrating another embodiment of the present invention in which theuse condition and normal condition sealing functions of the access portare performed by a separate component in the access port;

FIG. 8 is a cross sectional view substantially similar to that seen inFIGS. 6 and 7 in which a third embodiment of the present is providedwhere the use and normal condition sealing functions are separated andperformed by individual elements of the access device;

FIG. 9 is a cross-sectional view similar to that seen in FIG. 6illustrating another embodiment of the present invention showing anelongated self-flattening or self-occluding tube section which has notbeen penetrated by an inserted catheter: and

FIG. 10 is a cross-sectional view substantially similar to that seen inFIG. 9 illustrating an elongated self-flattening or self-occluding tubesection which has been penetrated by an inserted catheter or filament.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now in detail to the drawings illustrating the variousembodiments of the present invention, an access port 10 embodying theprinciples of the present invention is respectively illustrated inFIG. 1. The access port 10 includes a housing 12 formed from twoseparate components, a central body 14 and a discharge plug 16. The plug16 is provided with threads 18 which engage corresponding threads formedin the body 14. These and other features of the access port 10 providethe capability of constructing the access port 10 out of two separatematerials. The body 14 can be formed of a hard material which isresistant to penetration and damage by a sharp accessing instrument suchas a needle. The plug 16 can be formed from a less hard and cheapermaterial such as a polymer since it is not directly exposed to orengaged by a sharp accessing instrument. The housing 12 is also providedwith a substantially flat base 20 which operates to define a surfacewhich will support the port 10 in a location within the body of thepatient. Apertures 22 may be defined in the base to permit securement ofthe port 10 (by staples, sutures or other means) in a specific locationand to a specific tissue within the body of a patient.

Defined in one end of the body 14 is inlet orifice 24 which is definedby a funnel shaped surface 25. The funnel shaped surface 25 and theinlet orifice 24 operate as a target area at which the accessinginstrument (not shown) is directed through a percutaneous route.

In the event that the person attempting to access the port 10 completelymisses the entrance orifice 24, the accessing instrument may progressalong the exterior of the port generally towards the discharge plug 16and the implanted catheter 17 attached thereto. However, the accessinginstrument is prevented from engaging or otherwise contacting theimplanted catheter 17 by a pair of deflecting or shielding surfaces 26.These surfaces 26 are curved surfaces which laterally diverge from aleading edge 28 that is generally oriented along a central axis of thehousing 12. Upon striking the shielding surfaces 26, the sharp accessinginstrument will be deflected away from the central axis of the housing12 and away from the internal catheter 17. Obviously, different shapesand structures could be utilized to shield the internal catheter 17 froman errant accessing instrument. Of course, such equivalents are deemedto be within the purview of the present invention.

A properly directed accessing instrument is guided by the funnel shape25 of the entrance orifice 24 into a first or inlet passageway 30through the housing 12. The inlet passageway 30 defines an inlet axis 31which is redirected or angularly oriented with respect to a center axisdefined through the funnel shaped surface 25 of the entrance orifice 24.This change of direction by the inlet passageway 30 operates as a stopwhich prevents further insertion of a rigid accessing instrument such asa metal needle through the access port.

The inlet passageway 30 terminates and opens into an enlarged generallycylindrical cavity 32 in which is received an articulating cathetervalve assembly 34. In the illustrated embodiments of FIGS. 3-5, theaccess port 10 of the present invention is provided with a leaflet valveassembly including a pair of resilient disks 36 each of which has atleast one slit 38 defined partially across its center. Preferably theslits 38 will be oriented on mutually perpendicular axes with respect toone another. Adhesive 40 may be applied between the disks 36 to maintaina desired rotational indexing of the two disks 36. A doughnut or ringvalve 42 having a central aperture 44 is located downstream of the disks36 and may or may not be adhesively secured thereagainst. As seen inFIG. 3, the leaflet valve assembly 34 is maintained within the cavity 32by the threading of the plug 16 into engagement with the threads 18 onthe central body 14.

Upon detailed inspection of FIG. 3, it will be noticed that the centerline or cavity axis 35 through the middle of the leaflet valve assembly34 and cavity 32 does not coaxially correspond with the inlet axis 31 ofthe inlet passageway 30. While generally oriented in a common verticalplane, the two axes 31 and 35 are angled relative to one another. Theangularity of the cavity axis 35 can be either inclined or declinedrelative to inlet axis 31. As illustrated, the cavity axis 35 isinclined relative to the inlet axis 31. Additionally, at the end ofinlet passageway 30 it can be seen that the cavity axis 35 and valveassembly 34 are vertically offset from the inlet axis 31 and the inletpassageway 30. While shown as being offset vertically downward,depending on the angularity between the two axes 31 and 35 and thedistance between the inlet passageway 30 and the outlet passageway, theoffset could also be vertically upward. In other words, where theentrance orifice 24 is oriented downwardly (as seen in FIG. 3) and theinlet passageway 30 is angled upward with respect thereto, the cavity 32and the leaflet valve assembly 34 will be offset vertically downwardfrom the inlet passageway.

This offset is provided so as to accommodate the resiliency of aninserted flexible filament such as a catheter, guide wire, steering wireoptical fiber or other device, hereinafter catheter 46. As seen in FIG.3, after maneuvering the bend of the inlet passageway 30, the resiliencyor bias of the catheter 46 is toward the outward side of the bend in theinlet passageway 30. In the illustrated embodiments this bias is awayfrom the skin downward or to the interior of the patient's body. Byoffsetting the cavity 32 and leaflet valve assembly 34 as describedabove, the external catheter 46 is caused to engage the center of theleaflet valve assembly 34 thereby minimizing wear and ensuring properengagement.

Proceeding from the cavity 32, an outlet passageway 48 is definedthrough the discharge plug 16 and the discharge fitting 50 to which theinternal catheter 17 is mounted. The outlet passageway 48 is constructedso that an inserted catheter 46 cannot be completely passed through theoutlet passageway 48 to a point where it would extend beyond theterminal end of the fitting 50 and into the implanted catheter 17. Thisis achieved in one embodiment by convergently tapering the interiordiameter of the outlet passageway 48 in a smooth manner in the directionof the terminal end of the fitting 50. This tapering is generallydesignated at 52 and is such that the outlet passageway 48circumferentially engages the exterior perimeter of the catheter 46providing a positive stop which can be felt upon inserting the catheter46. This tactile feel provides an indication that the device has beenproperly accessed and the accessing filament placed in a proper dockedcondition. This feature is particularly useful when physical presence ofthe inserted catheter within the implanted catheter is not desired.

Alternatively, the taper 52 of the outlet passageway 48 can be formed ina molded elastomeric section 19 which is in turn insert molded into thedischarge plug 16. This is seen in FIG. 3b. Such a construction woulddecrease machining costs and the molded section 19 would itself providea positive stop for the catheter 46, a perimeter seal for the catheter46 and would inherently provide a degree of adhesion resisting theinadvertent pulling out of the catheter 46. Further, ribs could beformed on the tapered interior passageway to provide a tactileperception of when full insertion of the catheter 46 occurred.

In the above two embodiments, if the accessing catheter is of theappropriate size, the taper of the passageway will not operate as astop, but will only provide for a perimeter seal around the accessingcatheter while still allowing the catheter to be further inserted. Thiscan be configured so that the perimeter seal is achieved either beforeor after the accessing catheter reaches the implanted catheter. As such,this feature might prove desirable in a reduced flow or home infusionsettings and is further described below.

An alternative embodiment of the positive stop for an external catheteris generally illustrated in FIGS. 5 and 5a where the port 10 isidentical to the port 10 illustrated in FIGS. 1-4 except for thespecific structure of the positive stop. In this alternative embodiment,the previously mentioned smooth taper 52 in the outlet passageway 48 isreplaced with a series of progressively reduced diameter steps 54. Thesteps 54 operate in the same manner as the taper 52 in that the catheter46 is introduced and extended through the housing 12 until its terminalend engages the reduced diameter step 54 which closely approximates theexterior diameter of the catheter 46. At that point, the terminal end ofthe catheter 46 will engage the rise of one of the steps 54. Duringinsertion of the catheter 46, this positive engagement of the catheter46 with the step 54 will be felt through the catheter 46 by the personinserting the catheter 46 thereby providing a positive indication thatthe catheter 46 has been properly and fully introduced into the port 10.

As seen in FIGS. 3, 3a, 3b, 5 and 5a, the terminal end of the catheter46, in this case a catheter, may itself be tapered in a slightlyconverging manner. This not only allows for easier initial insertion ofthe catheter 46 into the port 10, but also ensures that a good perimeterseal is made between the exterior surface of the catheter 46 and thesurfaces defining the catheter stop in the outlet passageway 48.

While the embodiments of the positive stop illustrated in FIGS. 3 and 5perform a function of establishing a perimeter seal about the terminalend 56 of the catheter 46 for use condition sealing, the primaryfunction of establishing a perimeter seal about the catheter 46 isperformed by the doughnut valve of the leaflet valve assembly. It can beseen that the function of providing normal condition and use conditionsealing through the port are provided by a single valve assembly. InFIGS. 6, 7 and 8, three alternative embodiments are provided where thefunctions of preventing backflow through the port 10 when it is notbeing used (normal condition sealing) and establishing a perimeter sealabout the catheter 46 during infusion (use condition sealing) areperformed by two separate structures which are in turn spaced apart fromone another along the passageway through the port 10. In two of theembodiments (FIGS. 6 and 8), the fluid pressure of the infused fluid isutilized to open the valving structure which, in the normal condition,prevents backflow through the port 10. In the other embodiment (FIG. 7),the valving structure is engaged by the inserted catheter 46 and opened.Accordingly, the perimeter sealing structure is located downstream ofthe valving structure in this latter embodiment and upstream of thevalving structure in the other two embodiments. Again, as these termsare being used herein, upstream and downstream are to be determinedrelative to the source for the accessing catheter.

Referring now to FIG. 6, it can be seen that a tube valve 58, theillustrated being a self-flattening occlusive conduit 58, isfrictionally engaged over the barbs 51 of the discharge fitting 50. Theopposing end of the conduit 58 is secured to the implanted catheter 17through a conventional attaching method. The occlusive conduit 58 isconstructed of a resilient material and in a manner which causes theconduit 58 to flatten and completely occlude when the fluid pressure onthe inside of the conduit 58 is less than or equal to the pressureacting on the exterior of the conduit 58. As seen in FIG. 6, the conduit58 is fully occluded and prevents the backflow of fluid through theinternal catheter 17 and into the access port 10. Upstream of theconduit 58, generally at the end of the inlet passageway 30, an O-ringor similar sealing member 60 is located and held within a recessedgroove defined in the body 14. The internal diameter of the O-ring 60 isslightly greater than the tapered terminal end 56 of the catheter 46 butis slightly less than the maximum diameter of the catheter 46 at thatlocation when the catheter 46 is fully inserted into the housing 12. Inthis manner, the O-ring 60 will engage the outer diameter of thecatheter 46 and form a perimeter seal about the catheter 46 during theinfusion through the port 10 thus providing use condition sealing. Thediameter of the O-ring 60 is such that it does not limit or inhibitinsertion or withdrawal of the catheter 46.

As briefly mentioned above, in some applications, it may be possible toprovide use condition sealing strictly through the engagement betweenthe accessing catheter 46 and the conduit 58, eliminating the need forO-ring 60. In such an embodiment, shown in FIGS. 9 and 10, the accessingcatheter 46 is provided with a predetermined diameter that allows it toenter into and through the collapsible conduit 58, which may or may notbe unitarily formed with the implanted catheter 17. With the diameter ofthe accessing catheter 46 approximating or being slightly greater thanthe diameter of the conduit 48 when inflated, a perimeter seal will beformed about the accessing catheter 46 between it and the conduit 48 andan extremely small access port 10 can be constructed.

Alternatively, the tube valve 58 could be embodied as a slit in the tipor side of the catheter 17 itself, the slit being resiliently biased ina closed condition by the natural state or condition of the tube andopening upon an increased pressure within the catheter 17. In a furtherembodiment, the catheter 17 could be provided with an internalstructure, such as a bladder, defining the slit.

Referring now to FIG. 7, it can be seen that the leaflet valve assembly34 of FIG. 5 has been replaced with a flapper valve assembly 64. Theflapper valve assembly 64 operates as a one-way check valve and preventsthe backflowing of fluid through the port 10 in the normal condition.Accordingly, the flapper valve assembly 64 is provided with a resilientmember or flapper 66 which is deflected out of sealing engagement withthe remainder of the flapper valve assembly 64 during insertion of thecatheter 46 into the port 10. Downstream of the flapper 66 is an O-ring68 whose inner diameter is such that it will engage the exterior of theinserted catheter 46 and form a perimeter seal therearound duringinfusion of medicaments through the port 10. The O-ring 68 is locatedwithin the outlet passageway 48 received within a recessed groove 70 andoperates in a similar fashion to the O-ring 60 in FIG. 6. Upstream ofthe flapper 66, the flapper valve assembly 64 includes an elastomericdisk 72 having an aperture 74 which is greater than the outer diameterof the catheter 46. This disk 72 defines the surfaces against which theflapper 66 is sealing engaged when infusion is not being performed.

The final embodiment of the present invention is illustrated in FIG. 8.This embodiment has some similarities to the embodiment of FIG. 6 inthat the normal condition backflow preventing function of the accessport 10 is performed by a valve assembly located downstream from aseparate structure which performs the use condition perimeter sealingfunction during infusion. The normal condition sealing function isperformed in this embodiment by a ball check valve assembly 74.

In this valve assembly 74, a ball 76 is located within a chamber 78defined within a housing 80. The ball 76 is biased by a spring 82against the flow of infused fluids and will engage a valve seat 84generally adjacent to the inlet fitting 86 of the housing 80. The inletfitting 86 is attached by a conduit connector 88 extended therebetweento the barbs 51 of the discharge fitting 50. The outlet fitting 90 ofthe check valve assembly 74 is threadably received into one end of thehousing 80 to enable changing and repair of the ball 76 and spring 82 ifand when needed. The opposing end of the outlet fitting 90 is connectedto the internal catheter 17 in a conventional and well known manner.

In the same manner as described above in connection with FIG. 6, anO-ring 60 is located within a recessed groove 62 defined in the body 14of the housing 12 and generally adjacent to the end of the outletpassageway 48. This O-ring 60 is similarly provided with an innerdiameter that is slightly less than the exterior diameter of thecatheter 46 at that location when the catheter 46 is fully inserted intothe port 10. Medicaments being infused through the catheter 46 provide apositive fluid pressure which is sufficient to overcome the biasingforce of the spring 82 and therefore causes the ball 76 to unseat fromthe valve seat 84 allowing the infused fluids to be provided to theinternal catheter 70 and the desired treatment sight. The O-ring 60accordingly forms a perimeter seal about the catheter 46 duringinfusion.

In addition to the above described style of check valve, the valveassembly 74 could utilize a construction in which a ball is capable ofbeing biased either upstream or downstream of a closed, center neutralposition where flow through the valve 74 is obstructed. Such a valveassembly 74 would permit both infusion and withdrawal of fluids from thepatient, depending on the pressure differential applied to the valveassembly 74.

While the above description constitutes the preferred embodiment of thepresent invention, it will be appreciated that the invention issusceptible to modification, variation and change without departing fromthe proper scope and fair meaning of the accompanying claims.

We claim:
 1. An implantable access device which permits the introductionof an external filament such as a catheter, guide wire or optical fiberinto a patient for communication with an internal catheter locatedwithin the body of the patient, said device comprising:a housing havingportions defining an inlet opening, an outlet opening, a passagewaycommunicating between said inlet and outlet openings, said passagewayincluding an inlet portion and an outlet portion, said inlet openingbeing generally funnel shaped and guiding an external filament insertedpercutaneously into said inlet portion of said passageway, said outletportion of said passageway terminating in said outlet opening and saidoutlet opening being defined in a nipple adapted for having the internalcatheter attached thereto; first sealing means for providing resistanceto the flow of fluid through said passageway when said external filamentis not present within said device yet allowing the transfer of fluidsthrough said passageway when said filament is present within saidpassageway; and second sealing means for engaging and sealing about theexterior perimeter of an external filament when inserted into saiddevice.
 2. An implantable device as set forth in claim 1 wherein saidsecond sealing means is separate and distinct from said first sealingmeans.
 3. An implantable access device as set forth in claim 1 whereinsaid second sealing means is a O-ring.
 4. An implantable access deviceas set forth in claim 1 wherein said second sealing means is a donutvalve.
 5. An implantable access device as set forth in claim 1 whereinsaid second sealing means is located downstream of said first sealingmeans.
 6. An implantable access device as set forth in claim 1 whereinsaid second sealing means is located upstream of said first sealingmeans.
 7. An implantable access device as set forth in claim 1 whereinsaid first sealing means comprises a leaflet valve.
 8. An implantableaccess device as set forth in claim 1 wherein said first sealing meanscomprises a flapper valve.
 9. An implantable access device as set forthin claim 1 wherein said first sealing means comprises a fluid actuatedcheck valve.
 10. An implantable access device as set forth in claim 8wherein said check valve is a ball check valve.
 11. An implantableaccess device as set forth in claim 8 wherein said ball check valve is aspring biased ball check valve.
 12. An implantable access device as setforth in claim 1 wherein said first sealing means includes a collapsibleconduit, said collapsible conduit collapsing and being substantiallyoccluded when pressure within said conduit is less than or equal topressure acting on the exterior of said conduit.
 13. An implantableaccess device as set forth in claim 12 wherein said collapsible conduitis attached to said nipple and adapted for attachment to the internalcatheter.
 14. An implantable access device as set forth in claim 12wherein said second sealing means comprises engagement between anexternal filament and said collapsible conduit, the external filamentbeing receivable within said collapsible conduit.
 15. An implantableaccess device as set forth in claim 1 wherein said second sealing meanscomprises engagement between an external filament and features formed bysaid housing passageway.
 16. An implantable access device as set forthin claim 1 wherein said first sealing means is separate and distinctfrom said housing.
 17. An implantable access device as set forth inclaim 1 wherein said second sealing means is defined by a convergentlytapered portion of said passageway.
 18. An implantable access device asset forth in claim 17 wherein said tapered portion tapers to a diameterpreventing passage of the filament therethrough.